(1) Field of the Invention
The invention relates to the fabrication of integrated circuit devices, and more particularly, to a method of fabricating a Schottky diode using a shallow trench structure to solve the leakage current problem in the fabrication of integrated circuits.
(2) Description of the Prior Art
The contact structure of a metal to a lightly doped silicon is known as a Schottky diode. Typically, Aluminum is the metal used. The aluminum material's directly touching the silicon substrate within the contact hole often causes junction spiking. A barrier metal layer such as titanium tungsten, titanium nitride, or the like has been added between the silicide and the aluminum material to reduce junction spiking. A platinum silicide (PtSi) layer, for example, is formed between the Al and the barrier metal and the silicon substrate. The traditional contact structure requires a small amount of silicon loss in the silicide formation. However, this will increase the sensitivity of the Schottky diode to leakage caused by the metal pre-sputter etch. It is desired to find a method of making a Schottky diode structure without concern of junction leakage.
U.S. Pat. No. 4,835,580 to Havemann et al teaches a method of embedding a Schottky barrier diode within a bipolar transistor. They use a deep trench to increase diode area and decrease diode series and base-collector capacitance. U.S. Pat. No. 5,583,348 to Sundaram shows a method for forming a Schottky diode within a contact opening where a platinum silicide layer is deposited at the bottom of the opening. U.S. Pat. No. 5,166,094 to Kapoor teaches a method of forming Schottky diodes in base coupled transistor logic.